Polyester bicomponent filaments have been disclosed, for example in U.S. Pat. No. 3,671,379. Woven stretch fabrics comprising polyester bicomponent filaments have been disclosed, for example in U.S. Pat. Nos. 5,922,433 and 6,782,923. The fabrics disclosed in these references are comprised of bare bicomponent filaments and have strong synthetic appearance and hand due to the exposure of the bicomponent filaments on the fabric surface.
Core spun yarns containing polyester bicomponent filaments and fabrics comprising them have been disclosed. For example, Japanese patent applications JP2003-221742A and JP2003-221743A disclosed single and double wrapped bicomponent stretch yarn in which polyester bicomponent filaments are twisted and covered by cotton spun yarns. Japanese patent applications JP2003-073940A and JP2003-073942A disclose polyester bicomponent filament core spun yarns in which the bicomponent filaments are covered with animal fur, for example wool. However, the bicomponent filaments are exposed on the surface of the core spun yarns and on the fabrics comprising them.
Such exposure, or “grin-through,” is undesirable in apparel applications because the bicomponent filaments can be seen and felt. This results in the fabric having a glittery look and a hot, synthetic hand. In order to reduce grin-through, it is necessary to dye the fabric in two separate dyeing steps, which is a high cost and tedious process. Furthermore, it is difficult to match the color of the sheath staple fiber to that of the bicomponent filament core. Core spun yarns comprising polyester bicomponent filaments which do not have exposure of the bicomponent filaments are still sought. Fabrics comprising such yarns, which have improved appearance and hand, are also sought.